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Since 1963, transverse '''[[leaf springs]]''' have been an integral part of the suspension of '''[[General Motors|GM]]''''s '''[[Chevrolet Corvette]]'''. This article concerns the practical differences between leafs and coils, popular misconceptions, and the design considerations that led to their inclusion in the Corvette.  
{|border=0 align=right
|-
|{{Infobox Automobile
|name          = Chevrolet Corvette (sixth generation)
|image          = [[Image:CorvetteC6's silver.jpg|250px|C6 Corvette]]
|manufacturer  = [[Chevrolet]]
|parent_company = [[General Motors]]
|production    = 2005–
|predecessor    = [[Chevrolet Corvette C5]]
|processor      = [[Chevrolet Corvette C6]]
|class          = [[Sports car]]
|transmission  = 4-speed automatic (2005)<Br>6-speed [[Automatic transmission|automatic]] (2006&ndash;present)<Br>6-speed [[Manual transmission|manual]]
|assembly      = [[Bowling Green, Kentucky]], [[USA]]
|layout        = [[FR layout]]
|wheelbase      = {{Auto in|105.7|0}}
|platform      = [[GM Y platform|Y-body]]
|similar        = [[Dodge Viper]]<br>[[Porsche 911]]
}}
|-
|{{Infobox Automobile generation
|name          = Base model
|image          = [[Image:Chevrolet Corvette C6 coupe.jpg|250px|Chevrolet Corvette C6 coupe]]
|production    = 2005–
|length        = {{Auto in|174.6|0}}
|width          = {{Auto in|72.6|0}}
|height        = Coupe: {{Auto in|49|0}}<Br>2005-06 Convertible: {{Auto in|49.2|0}}<br>2007&ndash;present Convertible: {{Auto in|49.1|0}}
|engine        = 6.0&nbsp;[[Liter|L]] ''[[GM LS engine#LS2|LS2]]'' [[V8]] (2005&ndash;2007)<br>6.2&nbsp;L ''[[GM LS engine#LS3|LS3]]'' [[V8]] (2008&ndash;present)
|body_style    = 2-door [[coupe]]<br>2-door [[convertible]]
}}
|-
|{{Infobox Automobile generation
|name          = Z06
|image          = [[Image:CorvetteC6Z06yellow.jpg|250px|2006 Chevrolet Corvette Z06]]
|production    = 2006–
|predecessor    = [[Chevrolet Corvette C5#Z06|C5 Z06]]
|engine        = 7.0&nbsp;L ''[[GM LS engine#LS7|LS7]]'' [[V8]]
|body_style    = 2-door [[coupe]]
|length        = {{Auto in|175.6|0}}
|width          = {{Auto in|75.9|0}}
|height        = Coupe: {{Auto in|49.0|0}}
}}
|}


== Traditional use of leaf springs  ==
{{main|Chevrolet Corvette}}
[[Image:leafs1.jpg|right|thumb|230px|A traditional leaf spring arrangement.]]
The '''Chevrolet Corvette C6''' is the sixth and current generation of [[Chevrolet Corvette]]s. It was introduced in 2005, and according to several issues of ''[[Motor Trend]]'' magazine, will be superseded by the C7 Corvette in the 2012 calendar year.
A leaf spring is a long, flat, thin, and flexible piece of [[spring steel]] or composite material that resists bending. The basic principles of leaf spring design and assembly are relatively simple, and leafs have been used in various capacities since medieval times. Most heavy duty vehicles today use two sets of [[leaf springs]] per solid axle, mounted perpendicularly to support the weight of the vehicle. This system requires that each leaf set act as both a spring and a horizontally stable link. Because leaf sets lack rigidity, such a dual-role is only suited for applications where load-bearing capability is more important than precision in suspension response.


== Leaf springs on the Corvette ==
== Model details ==  
[[Image:leafs2.jpg|right|thumb|230px|The C5 Corvette's rear suspension.]]
Compared to the fifth generation, the "C6" gets an overhaul of the suspension geometry, all new bodywork with exposed headlamps (for the first time since 1962), a larger passenger compartment, a larger 6.0&nbsp;L (364&nbsp;cu&nbsp;in; 5967&nbsp;cc) [[Internal combustion engine|engine]], and a much higher level of refinement.<ref name="2006specs">http://media.gm.com/us/chevrolet/en/product_services/r_cars/r_c_corvette/06index.html#specs</ref>  Overall, it is 5.1 inches (13 cm) shorter than the [[Chevrolet Corvette C5|C5]], but its wheelbase has increased by 1.2 inches (3 cm). It is also one inch (2.5 cm) narrower. The 6.0&nbsp;L LS2 [[V8]] produces 400&nbsp;hp (298&nbsp;kW) at 6000&nbsp;rpm and 400 [[lb·ft]] (542&nbsp;[[N·m]]) of [[torque]] at 4400&nbsp;rpm.
All six generations of the Corvette have used leaf springs in some capacity. The basic arrangement for each generation is listed as follows:


*C1 (1953-1962): 
With an [[automatic transmission]], the Corvette achieves 15/25 [[Miles per gallon|mpg]] (city/highway); the [[manual transmission|manual-transmission]] model gets 16/26 mpg.<ref>[http://www.fueleconomy.gov/feg/compx2008f.jsp?year=2009&make=Chevrolet&model=Corvette&hiddenField=Findacar EPA estimate]</ref> The Corvette's manual transmission is fitted with Computer Aided Gear Shifting (CAGS), obligating the driver to shift from 1st directly to 4th when operating at lower RPMs. This boosts the [[United States Environmental Protection Agency|EPA]]'s derived fuel economy thus allowing the buyer to avoid paying the "gas guzzler" tax.
:Front: Independent unequal-length [[Double wishbone suspension|double wishbones]] with coil springs
:Rear:  Rigid axle supported by leaf springs and longitudinal control links <ref>http://faculty.delhi.edu/purdysd/62VettePhotos/FINF12.JPG</ref>
*C2 (1963-1967), C3 (1968-1982):
:Front: Independent unequal-length [[Double wishbone suspension|double wishbones]] with coil springs
:Rear: Independent suspension with trailing and lateral links supported by a centrally mounted leaf spring<ref>http://www.britishv8.org/Other/DaleRembold/DaleRembold-J.JPG</ref>
*C4 (1984-1996):
:Front: Independent unequal-length [[Double wishbone suspension|double wishbones]] with transverse fiberglass mono-leaf spring mounted to allow for anti-roll effect.
:Rear: Independent suspension with trailing and lateral links supported by a centrally mounted fiberglass mono-leaf spring
*C5 (1997-2004), C6 (2005-):
:Front: Independent unequal-length [[Double wishbone suspension|double wishbones]] with transverse fiberglass mono-leaf spring mounted to allow for anti-roll effect.
:Rear: Independent unequal length [[Double wishbone suspension|double wishbones]] with transverse fiberglass mono-leaf spring mounted to allow for anti-roll effect.


In the C2 and subsequent generations, a leaf spring is mounted transversely in the chassis and used in conjunction with several independent suspension designs. Common to these post-C1 Corvettes, the leaf acts only as a spring, and not a suspension arm or a link. Because it is not required to stabilize the wheels, the leaf functions in much the same manner as a coil spring. This configuration obviates the drawbacks and imprecision associated with traditional Hotchkiss (non-transverse leaf spring) suspensions.   
For the 2008 model, the Corvette receives a new engine, the [[LS3]].  With displacement increased to 6.2 liters (376&nbsp;cu&nbsp;in; 6162&nbsp;cc)<ref name="2009specs">http://media.gm.com/us/chevrolet/en/product_services/r_cars/r_c_corvette/09index.html#specs</ref> , power is increased to {{Convert|430|hp|kW|0|abbr=on}} and {{convert|424|lbft|Nm|0|abbr=on}} of torque, or {{Convert|436|hp|kW|0|abbr=on}} and {{convert|428|lbft|Nm|0|abbr=on}} with the optional vacuum actuated valve exhaust.<ref>{{cite web
| title = LS3 Overview - GM Powertrain
| url = http://media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Gen%20IV/Gen%20IV%20Car/08%20LS3.doc
| publisher = GM
| format = {{DOClink}}
}}</ref>  The previous [[Transmission Technologies Corporation|Tremec]] T56 transmission on manual Corvettes was replaced with a new version, the TR6060, in model year 2008.<ref>{{cite web
| title = Six-Speed Manual Tremec T56 (MM6/M12) Car Transmission
| url = http://media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Transmissions/2008%20Manual%20Transmission/08_MM6_MZ6.doc
| publisher = GM
| format = {{DOClink}}
| accessdate = 2008-11-27
}}</ref>  Manual Corvettes have improved shift linkage; the automatic model is set up for quicker shifts, and (according to Chevrolet) goes from [[0 to 60 mph]] in 4.3 seconds, faster than any other production automatic Corvette.<ref name="edmunds1">[http://www.edmunds.com/insideline/do/Drives/FirstDrives/articleId=120575 First Drive: 2008 Chevrolet Corvette<!-- Bot generated title -->]</ref>  According to automotive review website ''New Car Test Drive'', the Corvette's 0 to 60 time is actually 4.2 seconds, faster than both the [[Porsche 911|Porsche 911 Carrera]] and the [[Jaguar XK|Jaguar XK8]].<ref name="nctd-corvette2008">{{cite web |url=http://www.nctd.com/review-intro.cfm?Vehicle=2008_Chevrolet_Corvette&ReviewID=3652<!-- reprinted at e.g. http://autos.nytimes.com/2008/Chevrolet/Corvette/238/2661/290201/NCTD/researchReviews.aspx but no publication date there either --> |title=2008 Chevrolet Corvette |last=McCullough |first=Mitch |publisher=New Car Test Drive |accessdate=2008-11-22 }}</ref><!-- see "Driving Impressions" section --> The steering has also been tightened up for much improved feel. The wheels were also updated to a new five-spoke design.<ref name="edmunds1" />


Although commonly referred to as a "leaf spring suspension" it is more accurately called an independent double A-arm suspension.
==Z06==
The Corvette Z06 arrived as a 2006 model in the third quarter of 2005. It has a 7.0&nbsp;[[Liter|L]] (7,008&nbsp;cc/427.6&nbsp;cu&nbsp;in) version of the Small-Block engine codenamed ''[[GM LS engine#LS7|LS7]]''. The Z06 achieves a fuel economy of {{convert|15|mpgus|L/100 km mpgimp|abbr=on}} in the city and {{convert|24|mpgus|L/100 km mpgimp|abbr=on}} on the [[highway]],<ref>[http://www.fueleconomy.gov/feg/2008car1tablef.jsp?column=1&id=25387 EPA estimate]</ref> and the output is 505&nbsp;hp (376&nbsp;kW). [[Car and Driver]] recorded a 0-60 mph time of 3.6 seconds in their March 2007 comparison test.[http://www.caranddriver.com/assets/download/0703_hc_and_os_powertrain_ss.pdf]


=== Motion of a transverse leaf spring ===
In addition to the larger engine, the Corvette Z06 has a [[dry sump]] oiling system, and [[Connecting rod]]s made out of [[titanium]] alloy.


The following images show the movements of an independent suspension using a transverse leaf spring. For all images:
The Z06 officially weighs 3132&nbsp;lb (1421&nbsp;kg), giving it a weight to power ratio of 6.2&nbsp;[[Pound (mass)|lb]]/hp (3.8&nbsp;[[Kilogram|kg]]/kW).


* The suspension arms are green
===ZR1===
* The chassis is blue
{{main|Chevrolet Corvette C6 ZR1}}
* The uprights are gray
<!-- Deleted image removed: [[Image:Chevrolet Corvette ZR1 at 2008 NAIAS.JPG|thumb|left|Chevrolet Corvette ZR1 at 2008 [[NAIAS]]]] -->
* Leaf springs are dark gray
A Corvette variant was first reported by several print and online publications, based on rumor from General Motors was developing a production version of the Corvette above the Z06 level, under the internal code name ''Blue Devil'' (named after GM CEO [[Rick Wagoner]]'s alma mater, [[Duke University]]).  The car was originally rumored to feature a [[supercharger|supercharged]] [[GM LS engine|LS9]] engine producing more than {{Convert|650|hp|kW|0|abbr=on}} with prices reported to exceed $100,000 USD.<ref>[http://www.autoweek.com/apps/pbcs.dll/article?AID=/20060208/FREE/60208005&SearchID=73242362597113 Is Blue Devil Alive? Chevy Performance Might Be Heating Up] article from AutoWeek</ref>
* Pivot links connecting the ends of the springs to the suspension arms are red
<gallery>
Image:Down down split.JPG|1 - A transverse leaf spring suspension at rest, with separate right and left springs.
Image:Up down split.JPG‎ |2 - The same split-spring configuration with the left wheel in compression.
</gallery>


Illustrations #1 and #2 show independent left and right leaf springs mounted rigidly to a chassis. In the first illustration, the suspension is at rest. As a left wheel moves up in the second illustration, the left spring flexes upward, but the right spring remains unaffected. Because the two springs are not connected, the movement of one wheel has no effect on the spring rate of the opposite wheel. While the [[Chevrolet Corvette C2|C2]], [[Chevrolet Corvette C3|C3]], and [[Chevrolet Corvette C4|C4]] Corvettes used a continuous spring instead of the split spring of the illustration, left and right spring rates remained independent because the spring was rigidly mounted at its center to the chassis.  
The October 12, 2006 issue of ''[[AutoWeek]]'' published photos by photographer Chris Doane of a C6 with special auto-manufacturer-issued license plates on a Z06 with a hood bulge, widely thought to confirm the presence of a supercharger on the ''Blue Devil''.  Other names attached to the project included ''Corvette SS''<ref name="OctBlueDevil">[http://www.autoweek.com/apps/pbcs.dll/article?AID=/20061016/FREE/310160002&SearchID=73265024805840 Auto Week prototype Blue Devil photos]</ref> or ''Corvette Z07''.<ref name="MotorTrendZ07">[http://www.motortrend.com/features/auto_news/2007/112_0704_chevrolet_corvette_z07/  Z07 coming in late 2008] article by Motor Trend</ref>  In February 2007, a worker at a Michigan shipping company posted pictures online of a powertrain [[development mule]] that was being shipped to Germany, believed to be part of the ''Blue Devil'' program. The car had manufacturer's license plates, [[carbon-ceramic]] [[Disc brake#Discs|brakes]], enlarged fender vents, a hood bulge, and an engine with a positive-displacement supercharger in the valley between the cylinder banks and a [[Intercooler#Charge Cooling|water-to-air intercooler]] atop it. The photographer was fired and may face civil or criminal legal action, pending a GM investigation.


<gallery>
GM began to release details on the ''Blue Devil'' project in April 2007, and revealed the ZR1 in December.  The company confirmed the existence of the project in an interview with ''[[Car and Driver]]'' on April 13.  Power levels were confirmed to be between 600 and 700 horsepower (447 to 521&nbsp;kW), but contrary to prior rumors of a supercharged 6.2 liter engine, the engine was only confirmed to have greater displacement than the 7.0 liter LS7 in the Z06.<ref name="LutzCarAndDriverBlueDevil">[http://www.caranddriver.com/dailyautoinsider/12814/2009-corvette-blue-devil-confirmed-and-in-final-tuning-phase.html 2009 Corvette Blue Devil confirmed and in final tuning phase - Daily Auto Insider] article by Car and Driver</ref>  ''Motor Trend'' confirmed the official name for the production ''Blue Devil'', resurrecting the old ZR1 nameplate.  The ZR1 had originally been used on developmental cars in 1971, and again as ZR-1 as the top performance model on the [[Chevrolet Corvette C4|C4 Corvette]].<ref>[http://blogs.motortrend.com/6215473/car-news/corvette-blue-devil-finally-gets-a-name-zr1/index.html Corvette Blue Devil (finally) gets a name - ZR1]</ref> General Motors officially revealed the 2009 Corvette ZR1 on December 19, giving a press release and photographs of the car.  GM confirmed a supercharged 6.2&nbsp;L LS9 V8 producing {{convert|620|hp|abbr=on}}.  Performance figures were not released, but GM acknowledged that the car was capable of {{convert|200|mi/h|km/h|abbr=on}}, making it the fastest production Corvette ever.
Image:Dd linked.JPG‎|3 - A single transverse leaf spring suspension similar to that used on the C5 and C6 Corvette.
Image:Uu linked.JPG‎|4 - The same single-leaf suspension with both wheels compressed upward.
</gallery>  


Illustrations #3 and #4 show an independent suspension with a single transverse leaf spring, an arrangement similar to that used on the [[Chevrolet Corvette C5|C5]] and [[Chevrolet Corvette C6|C6]] Corvettes, and the front of the C4 Corvette. While at rest in illustration #3, the leaf forms a symmetric arc between the left and right sides of the suspension. Under the compression of both wheels in illustration #4, the widely-spaced chassis mounts allow the spring to pivot; the ends of the spring flex upward and the center moves down. <ref>Lamm, Michael. P44, The Newest Corvette. ©1984. [http://temp.corvetteforum.net/c4/gcrouse/Suspension/fiberglass_spring.gif]</ref>
[[Carbon fiber]] is used on the roof, hood, fenders, front splitter, and rocker moldings; the hood and fenders are painted over, while the roof and splitter are merely covered in a clear-coat, retaining their black color.  A [[polycarbonate]] window is placed in the center of the hood, allowing the engine intercooler to be seen from the exterior. The wheels are the largest ever placed on a production Corvette, with both front and rear wheels increasing in size and diameter over the Corvette Z06.  Carbon-ceramic brakes are included. The brake calipers are painted blue, as are the engine intercooler trim and the ZR1 logo.  Magnetic Selective Ride Control is also included on the car, with sensors to automatically adjust stiffness levels based on road conditions and vehicle movement.<ref>{{citenews | url = http://www.leftlanenews.com/chevrolet-corvette-zr1.html#more-5673 | title = 2009 Chevrolet Corvette ZR1 unveiled | publisher = Leftlanenews.com | date = 2007-12-19 | accessdate = 2007-12-19}}</ref>


=== The leaf spring as an anti-roll bar ===
==C6.R==
{{main|Chevrolet Corvette C6.R}}
[[Image:Le Mans 2005 CorvetteC6R.jpg|thumb|right|C6.R]]
The C6.R was a replacement for the C5-R, built by [[Pratt & Miller]], and unveiled for its first competition at the [[2005 12 Hours of Sebring]] endurance race of the [[American Le Mans Series]]. It came in second and third in its class, just behind the new [[Aston Martin DBR9]] racecar. It was put on display a week later at the [[New York International Auto Show]] next to the Z06.


The extent to which a leaf spring acts as an [[sway bar|anti-roll bar]] bar is determined by the way it is mounted. The fundamentals of this explanation appear in the Michael Lamm link at the end of this article, as well as in several patents. US Patent #6189904 <ref>http://www.google.com/patents?hl=en&lr=&vid=USPAT6189904</ref> is of particular relevance.
In 2006, the Corvette C6.R won both American Le Mans GT1 Championships: Teams and Manufacturers. On March 17, 2007 it won the GT1 class in the [[2007 12 Hours of Sebring|12 Hours of Sebring]].


A single, loose center mount would cause the spring to pivot about the center axis, and push one wheel down as the other was compressed upward. This is exactly opposite of an anti-roll bar, and has not been used on any generation of the Corvette.
For Le Mans 2007, four C6.R's were on the entry list, the two Corvette Racing entries joined by single entries from the Luc Alphand Aventures and PSI-Motorsport teams.


A single, perfectly rigid center mount that held a small center section of the spring flat against the frame would isolate one side of the spring from the other. No roll or anti-roll effect would appear. The rear spring of the C2, C3, and C4 has this type of mount, which effectively divides the spring in two. It becomes a quarter-elliptic spring.
The heart of the C6.R, its LS7.R motor, was crowned as Global Motorsport Engine of the Year by a jury of 50 race engine engineers on the Professional Motorsport World Expo 2006 in Cologne, Germany.


<gallery>
==Z06-R==
Image:Flexible central mount transverse leaf spring.JPG |A single transverse spring with a flexible center mount. When one side is pushed up the other side moves down. 
Entered in the [[FIA GT3 European Championship]] series as a GT3 class car, the Z06-R is a modified production Z06. Changes were necessary to make the car endurance race ready. These include a stripped interior, full rollcage for safety, center-locking wheels, carbon fiber doors, rear deck spoiler and front splitter. The engine and drivetrain are stock but the former is mapped for 98 octane race fuel. The result is a 7200&nbsp;rpm redline, 200 higher than stock and 10 extra horsepower. The car is not road legal.
Image:Semi-rigid central mount transverse leaf spring.JPG |A transverse leaf spring with a semi-rigid mount. When one side is pushed up the other side moves down significantly less than in the flexible mount case.
Image:Rigid central mount transverse leaf spring.JPG |A transverse leaf spring with a central rigid mount. The two spring halves are effectively isolated.  Movements of one half of the spring do not affect the other half.
</gallery>


The C2 and C3 Corvettes from 1963 until 1983 used a rear transverse leaf spring with a central rigid mount. The spring was constructed of multiple steel leafs with plastic anti-friction liners and closely-spaced mounts. These traits prevented it from acting as an anti-roll bar.  
Eight Z06-R were constructed by Callaway Competition GmbH<ref>[[Callaway Cars#C15 .28FIA Corvette GT3.29]]</ref> in [[Leingarten]], Germany, for the 2006 season. The French team Riverside campaigned a three car team.<ref>[http://www.vetteweb.com/events/vemp_0701_fia_gt3_corvette_racing/index.html 2006 Oscherleben Race]</ref> In an effort to achieve parity among the disparate participants of the GT3 Series, three forms of handicapping were applied by the FIA regulators: additional vehicle weight, ride height, and tire compound selection.  The Corvettes were raced with all three handicaps employed. The Z06R won the FIA GT3 European Championship in its second year of entry.<ref>[http://www.corvettemotorsport.com/dubai2.htm Victory in Dubai]</ref> Z06-Rs are also campaigned in national championships.


<gallery>
==Production notes==
Image:Trans-linked.JPG‎|5 - The single-leaf suspension with the left side in compression.
{|class=wikitable
Image:Trans-linked-back.JPG‎ |5a - The same suspension in rear profile.
!Year!!Production!!Base Price!!Notes
</gallery>
|- align=right
|2005||37,372||$44,245||align=left|New C6 body is first with fixed headlights since 1962; no Z06 model and a late convertible introduction
|- align=right
|2006||34,021||$43,800||align=left|Z06 debuts; 6-speed automatic with paddle shift available on non-Z06 models
|-
|- align=right
|2007||40,561||$44,250||align=left|6-speed automatic paddle shift delays are reduced drastically compared to 2006
|-
|- align=right
|2008||35,310||$46,950 ||align=left|Mild freshening, LS3 introduced, All leather interior added (LT4, LZ3)
|-
|}


Since the C4, the Corvette has had widely-spaced double mounts on the front. The rear spring has had double mounts since the C5. The spring is allowed to pivot about these two points. When only one wheel is compressed as in illustration #5, the portion of the spring between the mounts assumes an "S" shape, bending in two directions. As a result, the spring force applied to the right suspension arm is reduced as the left side compresses, like an anti-roll bar. The [[caster angle|caster]], [[camber angle|camber]], [[toe-in]], and general orientation of the left wheel remain unchanged.
==References==
 
<references />
This anti-roll effect is the result of the compound bend, the "S-bend", that the spring must make when the wheels are not level. A compound bend requires the spring to assume a tighter bend radius. The tighter bend radius requires more force than a larger one thus greater force must be applied to the spring.
 
<gallery>
Image:Corvette leaf spring all bends.JPG‎|This multi exposure image shows an exaggerated view of the leaf spring flex when the wheels are compressed, in droop and in roll.  The S-bent spring is shown in blue
</gallery>
 
When both wheels are level the force applied by the spring to the suspension is even between the sides.
<gallery>
Image:Corvette leaf spring flexed down.JPG‎|At static ride height the leaf spring applies the same 300lb to each side of the suspension.
Image:Corvette lead spring flexed down.JPG‎|In compression the spring force has increased to 500lb but is still even between both sides
</gallery>
 
When only one side of the suspension is compressed, the leaf spring is forced into an "S-bend" shape. This results in a compound bend in the spring, as opposed to the single bend in the case when the wheels are even.  The compound bend has the effect of increasing the stiffness of the spring on the side which is being compressed.  At the same time, the bend reduces the force on the side which is not compressed. 
 
<gallery>
Image:Corvette leaf spring S bend up-down.JPG‎|Left side shown in compression, right side shown at static height.  The left side spring force has increased from 500lbs to 600lbs while the right side has decreased from 300lb to 200lb. 
Image:Deformed spring model iso and plane.JPG|Approximate FEA model of a leaf spring under load.  The initial, unbent shape of the spring is shown as a silhouette box.  An upward deflection on the right side of the spring results in a smaller upward movement on the left side (shown with no static load)</gallery>
 
This transfer of force from one side to the other is exactly the same way an traditional anti-roll bar functions<ref>[http://vette.ohioracing.com/susp.html Suspension, The Quest For Neutral Steer<!-- Bot generated title -->]</ref>.  In the case of the Corvette the effects of the anti-roll bar and leaf spring are additive.  The operation of the leaf spring and anti-roll bar do not affect each other but their forces add together at the wheel<ref>http://en.wikipedia.org/wiki/Hooke%27s_law</ref>.  This additive property allows the Corvette engineers to use a smaller, lighter anti-roll bar as compared to using a separate left and right spring (coil or leaf).


Dave McLellan, chief engineer on the C4 Corvette program said the following about the front leaf spring setup<ref>Corvette from the Inside, Dave McLellan, p120</ref>:
==See also==
<blockquote>We planned to use a massive front ''[roll]'' bar to achieve the roll stiffness we were after.
We found, however, that by spreading the body attachment of the front suspension fiberglass spring into two separate attachments 18 inches apart, we could achieve a major portion of the roll stiffness contribution of the front roll bar for free.  We still used a massive front bar, but it would have been even bigger and heavier if it had not been supplemented by the leaf spring.
</blockquote>


== Transverse leaf springs within independent suspensions ==
* [[Chevrolet Corvette]]
* [[Nordschleife fastest lap times]]


=== Advantages ===
{{Corvette timeline}}
* Less [[unsprung weight]]. Coil springs contribute to unsprung weight; the less there is, the more quickly the wheel can respond at a given spring rate.
* Less weight. The C4 Corvette's composite front leaf weighed 1/3 as much as the pair of conventional coil springs it would replace.  Volvo reported that the single composite leaf spring used in the rear suspension of the 960 Wagon had the same mass as just one of the two springs it replaced.<ref>[http://www.designnews.com/article/CA151178.html COMPOSITE LEAF SPRINGS - Volvo<!-- Bot generated title -->]</ref>
* Weight is positioned lower. Coil springs and the associated chassis hard mounts raise the [[center of gravity]] of the car.
* Superior wear characteristics. The Corvette's composite leaf springs last longer than coils, though in a car as light as the Corvette, the difference is not especially significant. No composite Corvette leaf has ever been replaced due to fatigue failure, though steel leafs from 1963 to 1983 have been. As of 1980, the composite spring was an option on the C3.
* As used on the Corvette, ride height can be adjusted by changing the length of the end links connecting the leaf to the suspension arms.  This allows small changes in ride height with minimal effects on the spring rate.
* Also as used on the C4 front suspension, C5, and C6 Corvettes, the leaf spring acts as an [[sway bar|anti-roll bar]], allowing for smaller and lighter bars than if the car were equipped with coil springs. As implemented on the C3 and C4 rear suspensions with a rigid central mount, the anti-roll effect does not occur.
 
=== Disadvantages ===
* Packaging can be problematic; the leaf must span from one side of the car to the other. This can limit applications where the drivetrain, or another part, is in the way.
* Materials expense. Steel coils are commodity items; a single composite leaf spring costs more than two of them.
* Design complexity. Composite monoleafs allow for considerable variety in shape, thickness, and materials. They are inherently more expensive to design, particularly in performance applications.
* Cost of modification. Due to the specialized design and packaging, changing spring rates would require a custom unit. Coil springs in various sizes and rates are available very inexpensively. 
* Susceptibility to damage. Engine fluids and exhaust modifications like cat-back removal might weaken or destroy composite springs over time.  The leaf spring is more susceptible to heat related damage than conventional steel springs.
* Perception. Like [[pushrod]] engines, the leaf spring has a stigma that overshadows its advantages.
 
== Racing concerns ==
* Running stiffer springs left-to-right would require either asymmetrical spring mounts or an asymmetric spring.  However, a few companies such as VBP offer kits that allow independent adjustment of spring rate and ride height at all four corners of the car.
* Regulations often prohibit the use of leaf springs; NASCAR does not allow them.
* The more compact shape of a coil spring can allow for variation in more suspension design and spring placement. Because a transverse leaf spring must span the width of the car, open-wheel cars are too low to use them. The leaf spring would have to pass through the gearbox or the driver's legs.
* Coil springs are not car-specific. A Porsche, an LMP, and a Ferrari can all use a spring custom wound on the same generic equipment. Custom composite leaf springs require expensive retooling and cannot be used across car models.
* The characteristics of coil springs in a performance environment are known, and racers will use what they know. Most race teams do not have adequate experience with leaf springs to use them in this capacity.
 
Carroll Smith is quoted in his book, ''Engineer to Win''
:''If I were involved in the design of a new passenger vehicle, however, I would give serious consideration to the use of a transverse composite single leaf spring of unidirectional glass or carbon filament in an epoxy matrix. This would be the lightest practical spring configuration and, although space constraints would seem to limit its use in racing, it should be perfectly feasible on road-going vehicles, from large trucks to small commuter cars. (Since I wrote this paragraph the new-generation Corvette has come out with just such a spring to control its independent suspension systems-at both end of the car.)''
 
== Transverse leaf springs in other vehicles ==
In addition to the Corvette, a composite transverse leaf spring has been used on other GM and non-GM vehicles.
*[[Volvo]] 960 (Wagon only)
*Volvo S90
*Mercedes Sprinter vans (transverse in front only)
*VW 1-Litre-Car prototype car
*GM W-platform cars- (Lumina, Grand Prix, Regal, Cutlass Supreme).
*GM E-platform cars- (Eldorado, Toronado, Riviera, Reatta).
*Mercedes Smart ForTwo (used with MacPherson Struts)
*Indigo, a Swedish made, low volume roadster.  Due to the anti-roll properties of the transverse leaf spring setup the car does not use a separate front anti-roll bar.<ref>http://www.lakritz.se/nyheter/INDIGO.PDF</ref>
 
Many small European cars such as the [[Fiat]] 128, the Yugo, and the [[Triumph Motor Company]] small chassis cars (Herald, Vitesse, Spitfire, GT6) used transverse steel springs in similar fashion.  The Yugo's steel spring used twin attachment points and did provide anti-roll capability. 
 
Recent research on the design concept has been performed. 
In 2006 Ford Global Technologies was granted patent #7029017 for ''Wheel suspension for a motor vehicle with a transverse leaf spring'' <ref>http://www.google.com/patents?id=D0p3AAAAEBAJ&dq=7,029,017</ref>
 
==References==
{{Reflist}}
==External links==
* http://www.autozine.org/technical_school/suspension/tech_suspension1.htm
* http://www.circletrack.com/techarticles/ctrp_0602_leaf_springs/
* [http://www.google.com/patents?hl=en&lr=&vid=USPAT5425829&id=PcYlAAAAEBAJ&oi=fnd&dq=patent+5425829 GM Patent #5425829]- describing a method for creating variable rate composite leaf springs.  Includes background information on benefits to transverse leaf springs used with conventional suspension designs


[[Category:Chevrolet Corvette|Leaf springs]]
[[Category:Chevrolet Corvette|C6]]
[[Category:Springs (mechanical)]]
[[Category:Sports cars|Chevrolet Corvette C6]]
[[Category:Automotive suspension technologies]]

Latest revision as of 23:00, 9 February 2009

Chevrolet Corvette (sixth generation)
C6 Corvette
ManufacturerChevrolet
Parent companyGeneral Motors
Production2005–
AssemblyBowling Green, Kentucky, USA
PredecessorChevrolet Corvette C5
ClassSports car
LayoutFR layout
PlatformY-body
Transmission(s)4-speed automatic (2005)
6-speed automatic (2006–present)
6-speed manual
Wheelbase105.7 in (2685 mm)
ManualsService Manual
Base model
Chevrolet Corvette C6 coupe
Production2005–
Body style(s)2-door coupe
2-door convertible
Engine(s)6.0 L LS2 V8 (2005–2007)
6.2 L LS3 V8 (2008–present)
Length174.6 in (4435 mm)
Width72.6 in (1844 mm)
HeightCoupe: 49 in (1245 mm)
2005-06 Convertible: 49.2 in (1250 mm)
2007–present Convertible: 49.1 in (1247 mm)
Z06
2006 Chevrolet Corvette Z06
Production2006–
PredecessorC5 Z06
Body style(s)2-door coupe
Engine(s)7.0 L LS7 V8
Length175.6 in (4460 mm)
Width75.9 in (1928 mm)
HeightCoupe: 49.0 in (1245 mm)
Main article: Chevrolet Corvette

The Chevrolet Corvette C6 is the sixth and current generation of Chevrolet Corvettes. It was introduced in 2005, and according to several issues of Motor Trend magazine, will be superseded by the C7 Corvette in the 2012 calendar year.

Model details

Compared to the fifth generation, the "C6" gets an overhaul of the suspension geometry, all new bodywork with exposed headlamps (for the first time since 1962), a larger passenger compartment, a larger 6.0 L (364 cu in; 5967 cc) engine, and a much higher level of refinement.[1] Overall, it is 5.1 inches (13 cm) shorter than the C5, but its wheelbase has increased by 1.2 inches (3 cm). It is also one inch (2.5 cm) narrower. The 6.0 L LS2 V8 produces 400 hp (298 kW) at 6000 rpm and 400 lb·ft (542 N·m) of torque at 4400 rpm.

With an automatic transmission, the Corvette achieves 15/25 mpg (city/highway); the manual-transmission model gets 16/26 mpg.[2] The Corvette's manual transmission is fitted with Computer Aided Gear Shifting (CAGS), obligating the driver to shift from 1st directly to 4th when operating at lower RPMs. This boosts the EPA's derived fuel economy thus allowing the buyer to avoid paying the "gas guzzler" tax.

For the 2008 model, the Corvette receives a new engine, the LS3. With displacement increased to 6.2 liters (376 cu in; 6162 cc)[3] , power is increased to 430 hp (321 kW) and 424 lb·ft (575 N·m) of torque, or 436 hp (325 kW) and 428 lb·ft (580 N·m) with the optional vacuum actuated valve exhaust.[4] The previous Tremec T56 transmission on manual Corvettes was replaced with a new version, the TR6060, in model year 2008.[5] Manual Corvettes have improved shift linkage; the automatic model is set up for quicker shifts, and (according to Chevrolet) goes from 0 to 60 mph in 4.3 seconds, faster than any other production automatic Corvette.[6] According to automotive review website New Car Test Drive, the Corvette's 0 to 60 time is actually 4.2 seconds, faster than both the Porsche 911 Carrera and the Jaguar XK8.[7] The steering has also been tightened up for much improved feel. The wheels were also updated to a new five-spoke design.[6]

Z06

The Corvette Z06 arrived as a 2006 model in the third quarter of 2005. It has a 7.0 L (7,008 cc/427.6 cu in) version of the Small-Block engine codenamed LS7. The Z06 achieves a fuel economy of 15 mpg-US (16 L/100 km; 18 mpg-imp) in the city and 24 mpg-US (9.8 L/100 km; 29 mpg-imp) on the highway,[8] and the output is 505 hp (376 kW). Car and Driver recorded a 0-60 mph time of 3.6 seconds in their March 2007 comparison test.[1]

In addition to the larger engine, the Corvette Z06 has a dry sump oiling system, and Connecting rods made out of titanium alloy.

The Z06 officially weighs 3132 lb (1421 kg), giving it a weight to power ratio of 6.2 lb/hp (3.8 kg/kW).

ZR1

Main article: Chevrolet Corvette C6 ZR1

A Corvette variant was first reported by several print and online publications, based on rumor from General Motors was developing a production version of the Corvette above the Z06 level, under the internal code name Blue Devil (named after GM CEO Rick Wagoner's alma mater, Duke University). The car was originally rumored to feature a supercharged LS9 engine producing more than 650 hp (485 kW) with prices reported to exceed $100,000 USD.[9]

The October 12, 2006 issue of AutoWeek published photos by photographer Chris Doane of a C6 with special auto-manufacturer-issued license plates on a Z06 with a hood bulge, widely thought to confirm the presence of a supercharger on the Blue Devil. Other names attached to the project included Corvette SS[10] or Corvette Z07.[11] In February 2007, a worker at a Michigan shipping company posted pictures online of a powertrain development mule that was being shipped to Germany, believed to be part of the Blue Devil program. The car had manufacturer's license plates, carbon-ceramic brakes, enlarged fender vents, a hood bulge, and an engine with a positive-displacement supercharger in the valley between the cylinder banks and a water-to-air intercooler atop it. The photographer was fired and may face civil or criminal legal action, pending a GM investigation.

GM began to release details on the Blue Devil project in April 2007, and revealed the ZR1 in December. The company confirmed the existence of the project in an interview with Car and Driver on April 13. Power levels were confirmed to be between 600 and 700 horsepower (447 to 521 kW), but contrary to prior rumors of a supercharged 6.2 liter engine, the engine was only confirmed to have greater displacement than the 7.0 liter LS7 in the Z06.[12] Motor Trend confirmed the official name for the production Blue Devil, resurrecting the old ZR1 nameplate. The ZR1 had originally been used on developmental cars in 1971, and again as ZR-1 as the top performance model on the C4 Corvette.[13] General Motors officially revealed the 2009 Corvette ZR1 on December 19, giving a press release and photographs of the car. GM confirmed a supercharged 6.2 L LS9 V8 producing 620 hp (460 kW). Performance figures were not released, but GM acknowledged that the car was capable of 200 mph (320 km/h), making it the fastest production Corvette ever.

Carbon fiber is used on the roof, hood, fenders, front splitter, and rocker moldings; the hood and fenders are painted over, while the roof and splitter are merely covered in a clear-coat, retaining their black color. A polycarbonate window is placed in the center of the hood, allowing the engine intercooler to be seen from the exterior. The wheels are the largest ever placed on a production Corvette, with both front and rear wheels increasing in size and diameter over the Corvette Z06. Carbon-ceramic brakes are included. The brake calipers are painted blue, as are the engine intercooler trim and the ZR1 logo. Magnetic Selective Ride Control is also included on the car, with sensors to automatically adjust stiffness levels based on road conditions and vehicle movement.[14]

C6.R

Main article: Chevrolet Corvette C6.R
C6.R

The C6.R was a replacement for the C5-R, built by Pratt & Miller, and unveiled for its first competition at the 2005 12 Hours of Sebring endurance race of the American Le Mans Series. It came in second and third in its class, just behind the new Aston Martin DBR9 racecar. It was put on display a week later at the New York International Auto Show next to the Z06.

In 2006, the Corvette C6.R won both American Le Mans GT1 Championships: Teams and Manufacturers. On March 17, 2007 it won the GT1 class in the 12 Hours of Sebring.

For Le Mans 2007, four C6.R's were on the entry list, the two Corvette Racing entries joined by single entries from the Luc Alphand Aventures and PSI-Motorsport teams.

The heart of the C6.R, its LS7.R motor, was crowned as Global Motorsport Engine of the Year by a jury of 50 race engine engineers on the Professional Motorsport World Expo 2006 in Cologne, Germany.

Z06-R

Entered in the FIA GT3 European Championship series as a GT3 class car, the Z06-R is a modified production Z06. Changes were necessary to make the car endurance race ready. These include a stripped interior, full rollcage for safety, center-locking wheels, carbon fiber doors, rear deck spoiler and front splitter. The engine and drivetrain are stock but the former is mapped for 98 octane race fuel. The result is a 7200 rpm redline, 200 higher than stock and 10 extra horsepower. The car is not road legal.

Eight Z06-R were constructed by Callaway Competition GmbH[15] in Leingarten, Germany, for the 2006 season. The French team Riverside campaigned a three car team.[16] In an effort to achieve parity among the disparate participants of the GT3 Series, three forms of handicapping were applied by the FIA regulators: additional vehicle weight, ride height, and tire compound selection. The Corvettes were raced with all three handicaps employed. The Z06R won the FIA GT3 European Championship in its second year of entry.[17] Z06-Rs are also campaigned in national championships.

Production notes

Year Production Base Price Notes
2005 37,372 $44,245 New C6 body is first with fixed headlights since 1962; no Z06 model and a late convertible introduction
2006 34,021 $43,800 Z06 debuts; 6-speed automatic with paddle shift available on non-Z06 models
2007 40,561 $44,250 6-speed automatic paddle shift delays are reduced drastically compared to 2006
2008 35,310 $46,950 Mild freshening, LS3 introduced, All leather interior added (LT4, LZ3)

References

  1. ↑ http://media.gm.com/us/chevrolet/en/product_services/r_cars/r_c_corvette/06index.html#specs
  2. ↑ EPA estimate
  3. ↑ http://media.gm.com/us/chevrolet/en/product_services/r_cars/r_c_corvette/09index.html#specs
  4. ↑ "LS3 Overview - GM Powertrain" (DOC (computing)DOC). GM. http://media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Gen%20IV/Gen%20IV%20Car/08%20LS3.doc. 
  5. ↑ "Six-Speed Manual Tremec T56 (MM6/M12) Car Transmission" (DOC (computing)DOC). GM. http://media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Transmissions/2008%20Manual%20Transmission/08_MM6_MZ6.doc. Retrieved on 2008-11-27. 
  6. ↑ 6.0 6.1 First Drive: 2008 Chevrolet Corvette
  7. ↑ McCullough, Mitch. "2008 Chevrolet Corvette". New Car Test Drive. http://www.nctd.com/review-intro.cfm?Vehicle=2008_Chevrolet_Corvette&ReviewID=3652. Retrieved on 2008-11-22. 
  8. ↑ EPA estimate
  9. ↑ Is Blue Devil Alive? Chevy Performance Might Be Heating Up article from AutoWeek
  10. ↑ Auto Week prototype Blue Devil photos
  11. ↑ Z07 coming in late 2008 article by Motor Trend
  12. ↑ 2009 Corvette Blue Devil confirmed and in final tuning phase - Daily Auto Insider article by Car and Driver
  13. ↑ Corvette Blue Devil (finally) gets a name - ZR1
  14. ↑ "2009 Chevrolet Corvette ZR1 unveiled". Leftlanenews.com. 19 December 2007. http://www.leftlanenews.com/chevrolet-corvette-zr1.html#more-5673. Retrieved on 19 December 2007. 
  15. ↑ Callaway Cars#C15 .28FIA Corvette GT3.29
  16. ↑ 2006 Oscherleben Race
  17. ↑ Victory in Dubai

See also

v • d • e
Chevrolet Corvette timeline, 1953–present
Type 1950s 1960s 1970s 1980s 1990s 2000s
3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
Coupe C2 C3 C5
Hatchback Collector Edition C4 C5 C6
Convertible C1 C2 C3 C4 C5 C6
Performance Fuel Injection L84 Big Block Big Block ZR-1 LT4 Z06 Z06
ZR1
Motorsports: Grand Sport • GTP • C5-R • C6.R
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